Dr. Matthew B. Sullivan's research focus is on the co-evolution of microbe and virus (phage) in environmental populations, as well as the impact of marine phages on microbe-mediated global biogeochemistry. Genomics and model-systems-based experimentation revealed that cyanobacterial phages often contain host photosynthesis genes, which are expressed during infection and act as a diversity generator for their numerically-dominant, globally-distributed photosynthetic hosts. Using a genomic and metagenomic toolkit, we query 'wild' viral populations to identify important hypotheses that can be evaluated using model-system approaches with appropriate phage isolates. The Sullivan lab is also developing single-cell assays to investigate questions that are critical for modeling and predicting the impacts of phage-host interactions in the wild. Specifically, these include gaining an understanding of the in situ host range of phage isolates, the metabolic capacity of to-date uncultured phage-host systems, the impacts of host growth status on phage production, and the fraction of microbial cells that are infected in wild populations.